Bromodeoxyuridine is a radiation sensitizing drug which sensitizes rapidly dividing cells. Thymidine is replaced by the uridinedeoxyriboside compound predisposing DNA to single strand breaks, as well as inhibiting single strand repair. BUdR has been used in the past in head and neck lesions, osteosarcoma, and particularly in glioblastoma and other brain tumors, but used to be felt to require intra-arterial delivery to be effective.